This report addresses the question of the trajectory correction and simultaneous reduction of the dispersion in the linacs of future linear colliders. With high frequencies for the acceleration wave, the effects of wake fields in the presence of finite trajectory distortions can be large and the subsequent transverse emittance dilution intolerable. Therefore, the beam trajectory has to be optimised in a suitable momentum range and a ‘‘dispersion‐free’’ algorithm has been proposed at SLAC, with this object. The present work describes an application of this method, with the aim to include in the model the nonlinearity with momentum of the lattice transfer‐coefficient. In this approach, the function to be minimized contains one term related to the on‐momentum trajectory as well as a finite number of terms associated with the momentum dependence of the dispersion, to increasing orders in &Dgr;p/p. The particular case of second‐order development is treated separately and an example is given for the CLIC beam.